TM 11-6625-2398-15-3
shown in solid lines, (fig. 6-3) and proceed as follows:
NOTE
This insertion loss must be slightly less (at
(1) On the signal generator, set the
least 0.2dB) than the insertion loss measured
MEGACYCLES dial to 1030 with the frequency control
between the RF IN/OUT and RF SUM jacks
knob. Set the function switch to CW, and turn on the
signal generator. Allow a minimum of 20 minutes warm-
up period before proceeding.
(8) Correct the hybrid attenuator calibration tag
marking, if incorrect.
(2) With the METER SCALE set to NORMAL and
INPUT SELECTOR set to XTAL200KΩ, turn on the
(9) Successively increase the ATTENUATOR DB
SWR indicator, and allow a minimum of 10 minutes
control, from the reading obtained in step (7), by 6, 9,
warm-up period before proceeding.
and 12. Record the readings on the meter of the SWR
indicator for the variable attenuator ATTENUATOR DB
(3) Turn off the signal generator and zero set the
control settings of plus 6dB, plus 9dB, and plus 12dB.
OUTPUT VOLTS meter.
(10) Reconnect the hybrid attenuator, solid lines
(4) Turn on the signal generator, and adjust the
OUTPUT LEVEL control knob for an OUTPUT VOLTS
meter indication at the SET LEVEL (+4DBM) mark, with
(11) Adjust the hybrid attenuator ATTENUATOR
the attenuator set to 0dB.
control for the same SWR indicator meter readings
recorded in step (12). Insertion losses must be within
NOTE
the following limits:
Check that OUTPUT VOLTS meter indication is
exactly on the SET LEVEL mark with the
Variable attenuator setting
Hybrid attenuator setting
Increased 6dB
13 + 2.0, -1.3dB
attenuator set to 0dB (outer scale). Readjust
Increased 9dB
16 +2.5, -1.3dB
the OUTPUT LEVEL control knob if required.
Increased 12dB
19 +3.0, -1.5dB
(5) On the signal generator, set the function switch
(12) Reset the signal generator MEGACYCLES
to 1000 the MOD. UP-NORMAL DOWN switch to
dial to 1090 and repeat steps (3) through (7).
NORMAL and adjust the MOD. LEVEL control for a
reading of 50 on the PERCENT MODULATION meter.
(13) Correct the hybrid attenuator calibration tag
Set the hybrid attenuator ATTENUATOR control to 0
marking for 1090MHz, if incorrect.
(zero). Adjust the SWR indicator VERNIER GAIN
control and the RANGE switch for an exact meter
(14) Repeat step (9) using the reading obtained in
reading (e.g., .5 on the DB meter scale). Record the
step (13) for the variable attenuator.
meter reading.
(15) Reconnect the hybrid attenuator, solid lines
(6) Disconnect the hybrid attenuator under test
and connect the variable attenuator, as shown by broken
lines, figure 6-3.
(16) Adjust the hybrid attenuator ATTENUATOR
control for the same SWR indicator meter readings
(7) Adjust the variable attenuator ATTENUATOR
recorded in step 14. Insertions losses must be within
DB control for the same SWR indicator meter reading
the following limits:
recorded in step b(5). Insertion loss on ATTENUATOR
DB control of the variable attenuator must indicate
Variable attenuator setting
Hybrid attenuator setting
6.511.5dB.
Increased 6dB
13 +2.0, -1.3dB
Increased 9dB
16 +2.5, -1.3dB
Increased 12dB
19 +2.5, -1.4dB
6-9
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